This invention relates to vehicle panel assemblies and, more particularly, to vehicle panel assemblies which are mounted to a vehicle with an adhesive.
Conventional window assemblies are mounted to the vehicle body by an adhesive and often in combination with one or more fasteners which are mounted on the window panel or are embedded in a gasket which has been previously extruded or molded on to the window panel. The adhesive often provides the primary attachment to the vehicle and is applied to the surface of the panel, for example by extrusion, after priming of the substrate surface (typically a glass substrate) and/or the vehicle body (typically metal or a composite material). The window assembly is then pressed against the mounting flange or decking of the vehicle body to which the adhesive adheres after curing. Heretofore, these adhesives have been moisture cured, for example the moisture cure BETASEAL brand adhesive available from Essex Specialty Products of Auburn Hills, Mich. These moisture cure urethane adhesives, however, are currently applied at the vehicle assembly line and require either robotic application or hand application. Furthermore, the moisture cure adhesives require relatively long cure times--these adhesives typically take on the order of 120 minutes to cure sufficiently to develop the required "decking" strength to hold the window assembly in place. Consequently, the window assemblies installed in this manner may require temporary support while moving along the assembly line. Furthermore, the full strength of the adhesive requires a cure of about 24 to 72 hours, depending on environmental conditions. In addition, these cure periods are sensitive to the surrounding environment. Where the manufacturing plant is located in an area having low humidity, the cure time is significantly longer than in an area having high humidity. Consequently, standardizing such installations is difficult.
In addition to the relatively long cure time, the chemicals forming the adhesive and the adhesive primers require special handling. The adhesive must be contained in a very low moisture or moisture-free environment before application onto the glass panel to avoid premature curing. Furthermore, the adhesive and primer chemicals require special clean-up procedures and inventorying to assure full effectiveness of the adhesive. Moreover, these chemicals require proper ventilation, and the personnel handling the chemicals require protective gear. Consequently, in-vehicle-plant applications are labor intensive, increase assembly linetime, potentially increase the frequency of down-time when the adhesive is improperly applied, for example when the adhesive is dripped on other areas of the vehicle, and are, therefore, costly.
More recently, proposals have been made to control the curing process of the adhesive by covering the adhesive with a barrier film which is then subsequently peeled off the bead at the assembly line to allow installation and curing. One such example is disclosed in U.S. Pat. No. 4,933,032 to Kunert. Kunert '032 also proposes the use of heat or irradiation to actuate a multi-component polyurethane adhesive, which contains an initiating or reaction component in inactivated form, for example in the form of micro-capsules, which are activated by the heat or irradiation before assembly of the glazing. While the removable barrier films and multi-component polyurethane adhesive theoretically remove the adhesive application process from the assembly line, numerous problems still remain. The extrusion and film application process is complicated, and the film can be vulnerable to tearing or damage during transportation. Furthermore, these films still require removal and disposal. Moreover, the barrier film must be accurately placed, otherwise, the exposed portions of the adhesive are prematurely cured and may be ineffective as a bonding agent.
The recent trend in vehicles is to produce a stream line or aerodynamic vehicle with larger windows to improve visibility. As a result the window assemblies often require compound curvatures. These compound curvatures make it hard to heat the panel uniformly. Furthermore, newer window panels include laminated substrates, moldings, and attachments which tend to degrade when subject to high temperatures. In order to heat such micro-capsule-containing adhesives over a period of time consistent with in-line processing, relatively high energy is required. In addition to possible degradation of the panel substrate, of the moldings, and of the attachments, the bead of adhesive is also subject to degradation if overheated. Perhaps for these and other reasons, heretofore, no "ready-to-install" window or panel assemblies have been successfully made or commercialized.
Consequently, there is a need for a "ready to install" panel assembly, for example a modular window, which can be quickly installed or "decked" in a vehicle or the like in an assembly line. Preferably, the modular window can be preassembled with an adhesive already applied at a location remote from a vehicle assembly plant to eliminate additional manufacturing time at the assembly line, handling of extra materials, on-line purging, which is required to eliminate unused portions of the moisture cured urethane in the dispenser nozzle, handling of chemistry in the vehicle manufacturing plant, including the adhesives and adhesive primers, and humidity control equipment and yet can be "decked" with the adhesive which is not activated until just prior to installation and which develops sufficient decking strength to hold the modular window in place.